# Copyright 2020 The Google Research Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Utility functions for processing motion clips."""

import os
import inspect

currentdir = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
parentdir = os.path.dirname(os.path.dirname(currentdir))
os.sys.path.insert(0, parentdir)

import numpy as np

from engineai_rl_lib.ref_state import pose3d
from pybullet_utils import transformations


def standardize_quaternion(q):
    """Returns a quaternion where q.w >= 0 to remove redundancy due to q = -q.

    Args:
      q: A quaternion to be standardized.

    Returns:
      A quaternion with q.w >= 0.

    """
    q[q[:, -1] < 0] = -q[q[:, -1] < 0]
    return q


def normalize_rotation_angle(theta):
    """Returns a rotation angle normalized between [-pi, pi].

    Args:
      theta: angle of rotation (radians).

    Returns:
      An angle of rotation normalized between [-pi, pi].

    """
    norm_theta = theta
    if np.abs(norm_theta) > np.pi:
        norm_theta = np.fmod(norm_theta, 2 * np.pi)
        if norm_theta >= 0:
            norm_theta += -2 * np.pi
        else:
            norm_theta += 2 * np.pi

    return norm_theta


def calc_heading(q):
    """Returns the heading of a rotation q, specified as a quaternion.

    The heading represents the rotational component of q along the vertical
    axis (z axis).

    Args:
      q: A quaternion that the heading is to be computed from.

    Returns:
      An angle representing the rotation about the z axis.

    """
    ref_dir = np.array([1, 0, 0])
    rot_dir = pose3d.quaternion_rotate_point(ref_dir, q)
    heading = np.arctan2(rot_dir[1], rot_dir[0])
    return heading


def calc_heading_rot(q):
    """Return a quaternion representing the heading rotation of q along the vertical axis (z axis).

    Args:
      q: A quaternion that the heading is to be computed from.

    Returns:
      A quaternion representing the rotation about the z axis.

    """
    heading = calc_heading(q)
    q_heading = transformations.quaternion_about_axis(heading, [0, 0, 1])
    return q_heading
